# Osteogenic differentiation by pre-osteoblasts is enhanced more on 3D-PRINTED poly-ɛ-caprolactone scaffolds coated with collagen and hydroxyapatite than on poly-ɛ-caprolactone/hydroxyapatite composite scaffolds coated with collagen

## TL;DR

3D-printed scaffolds coated with collagen and hydroxyapatite better support bone cell development than other types of scaffolds.

## Contribution

The study compares two scaffold types for bone tissue engineering and identifies which enhances osteogenic activity more effectively.

## Key findings

- PCL/col-HA scaffolds enhanced alkaline phosphatase activity and calcium deposition more than PCL-HA/col scaffolds.
- PCL-HA/col scaffolds improved pre-osteoblast proliferation and collagen deposition.
- Coating PCL scaffolds increased surface roughness and elastic modulus while reducing water contact angle.

## Abstract

Three-dimensional (3D)-printed poly-ε-caprolactone (PCL) scaffolds lack sufficient bioactivity for optimal bone tissue engineering applications. This shortcoming can be overcome by coating PCL scaffolds with collagen and hydroxyapatite (PCL/col-HA) or by applying a collagen coating to PCL-HA composite scaffolds (PCL-HA/col). Here we aimed to test which type of scaffold is more effective in stimulating osteogenic activity. Moreover, the scaffolds’ physicomechanical properties were characterized. 3D-printed PCL/col-HA containing 10, 20, or 30% HA particles, and 3D-printed PCL-HA/col containing 10, 20, or 30% HA particles with collagen coating were fabricated. MC3T3-E1 pre-osteoblasts were cultured on the scaffolds for 14 days. The physicomechanical properties of the scaffolds and pre-osteoblast functionality were evaluated through experiments and finite element (FE) modeling. We found that coating of PCL scaffolds with collagen and HA or coating of PCL-HA composite scaffolds with collagen changed the geometry and topography of the scaffold surfaces. Furthermore, PCL/col-HA and PCL-HA/col showed higher surface roughness and elastic modulus, but lower water contact angle, than PCL scaffolds. FE-modeling showed that all scaffolds tolerated up to 2% compressive strain, which was lower than their yield stress. 3D-printed PCL/col-HA and PCL-HA/col scaffolds promoted pre-osteoblast proliferation and osteogenic activity compared to unmodified PCL scaffolds. PCL-HA/col scaffolds increased pre-osteoblast proliferation and collagen deposition, whereas PCL/col-HA scaffolds increased alkaline phosphatase activity and calcium deposition. Osteogenic activity of pre-osteoblasts was more enhanced on 3D-printed PCL/col-HA scaffolds than on PCL-HA/col scaffolds, particularly in the short-term, which seems promising for in vivo bone tissue engineering.

Graphical Abstract